Device for withdrawing flakes or shavings from a donor bone by scraping

ABSTRACT

Device for withdrawing flakes or shavings from a donor bone by scraping, comprising an internally hollow handle (M) composed of a hollow body ( 1 ) with a cavity ( 11 ) and of slidable means for closing and respectively rendering accessible the cavity ( 11 ), and scraper means ( 20 ) positioned at the front end of said slidable means and comprising a gap for passage of the bone flakes or shavings into the cavity ( 11 ); said slidable means comprise an upper plate ( 6 ) positioned on the upper side of the hollow body ( 1 ) to close the cavity ( 11 ) and slidable on this latter, its front portion ( 7 ) being not joined to the hollow body ( 1 ) and being elastically deformable to move away from the front edge of this latter when under load. Said scraper means comprise a blade ( 20 ) positioned at the front end of said slidable plate ( 6 ), and having an active surface ( 21 ) perpendicular or nearly perpendicular to the longitudinal axis of the front portion of the handle (M).

TECHNICAL FIELD

[0001] The present invention relates to the surgical technique of bonetransplant, and in particular the withdrawal of bone fragments from adonor bone and their transplanting into a receiver bone which is to beat least partially reconstructed.

[0002] More precisely, the invention relates to the withdrawal of smallparticles of healthy bone in the form of shavings or flakes, to betransplanted into the tissue to be reconstructed, especially in facialand dental jawbone surgery.

[0003] The withdrawal is preferably effected on a bone of the samepatient, the withdrawn material being used to induce the re-growth ofbone where this is lacking either because of natural causes (atrophies)or because of provocation (traumas), or to regenerate bone defectsduring reconstruction, or again to enlarge weakened bone sections.

[0004] The problem confronted by the present invention is to withdrawand transfer bone flakes or shavings.

[0005] The material must be withdrawn without causing any damage to thebone itself or to the soft parts surrounding the area of intervention.It is therefore of fundamental importance that the withdrawal concernsonly the cortical part of the bone, without intervening on its medullaryor spongy part. A further requirement is to collect the withdrawn bonescales or shavings and to preserve them until their grafting into directcontact with the defective bone to be regenerated.

[0006] The final requirement is to render the withdrawal deviceinoffensive after use. In this respect, once used it becomes potentiallyinfected by its contact with blood and bone material, and must thereforebe protected to prevent the operator or the device disposal personnelbeing accidentally wounded, with serious danger of infection.

BACKGROUND ART

[0007] Although the available state of the art devices have provedsuitable for the purpose, they present defects and limitations whichneed to be eliminated. Devices are known, illustrated in U.S. Pat. No.5,683,406, comprising a cutting edge positioned on the front side of ahalf moon-shaped aperture provided at the end of a slidable plate whichcloses a cavity in a handle, the purpose of which is to collect theshavings.

[0008] The cutting edge of said half moon-shaped aperture emerges onthat side of the plate external to said cavity, and remains accessiblefrom the outside in any position of the plate.

[0009] The handle cavity is closed by a slidable plate which uncoversthe aperture for collecting the shavings which are formed by bringingsaid cutting edge into contact with the donor bone and sliding it alongthis latter while maintaining it pressed with a certain force.

[0010] This type of device presents a first defect deriving from thefact that the curved shape of the cutting edge intended to operate as ascraper makes it difficult to guide the instrument along the bone, inthe sense that the cutting edge tends to deviate to the right or to theleft of the path chosen by the surgeon.

[0011] Secondly, the pressure with which the cutting edge acts isdetermined essentially by the surgeon, with the double danger that theinstrument may escape from his hand with the evident risk of cutting orlacerating the soft tissue close to the withdrawal region, and thatexcessive pressure may cause serious undesirable injury to blood vesselsor, more dangerously, to nerves or tendons.

[0012] Finally, once used the device must be protected, because itscutting part remains exposed and can therefore accidentally woundwhoever comes into contact with it, with the risk of infection.

[0013] An object of the invention is to eliminate said problems withinthe framework of a simple and economical construction.

DISCLOSURE OF THE INVENTION

[0014] Said object is attained by a device having the characteristicsdefined in the claims.

[0015] It is composed of an internally hollow elongate handle of anycross-section of suitable shape, consisting of a hollow body having acavity, the upper face of which is closed by a slidable plate whichcloses and renders accessible the cavity and has its front end notjoined to the hollow body and elastically deformable so that it movesaway from the front edge of this latter when under load; at its frontend, said slidable plate carries a blade having an active surfaceperpendicular or nearly perpendicular to the longitudinal axis of thefront portion of the handle, and having its cutting edge of arcuateprofile to act as a scraper the cutting or scraping edge of which isdirected towards the hollow body and projects downwards from it.

[0016] The front end of the hollow body is shaped such that whilemaintaining its width unaltered, it degrades in height until it reachesthe cutting edge of the blade, which has a rounded surface to rest onthe donor bone.

[0017] The slidable plate is secured to the hollow body by slidableconnection means provided with stops which when the plate is in itsmaximum advancement position allow the blade to just project beyond theedge of the curved surface of the hollow body, whereas when the plate isretracted its position is such that the cutting edge of the blade isinaccessible from the outside.

[0018] At that end close to the curved surface of the body the plateconnection means terminate at a certain distance from the front edge ofsaid surface such that that portion of the plate which terminates withthe blade is projectingly supported elastically.

[0019] The materials of construction of the device are not critical,except for the blade which obviously has to be of steel, and for theslidable plate which has to have a certain elasticity.

[0020] Preferably both the hollow body and the slidable plate areconstructed of synthetic resin suitable for medical use, such aspolycarbonate or acrylonitrile/butadiene/styrene.

[0021] The merits and the operational and constructional characteristicsof the invention will be apparent from the ensuing detailed descriptionrelative to a preferred embodiment thereof given by way of non-limitingexample and illustrated by the figures of the accompanying drawings.

[0022]FIG. 1 is a three-quarter perspective view from above, showing thedevice of the invention in the closed position.

[0023]FIG. 2 is another perspective view from a slightly displacedviewing point, showing the same device in the open position.

[0024]FIG. 3 is a side view of the device in the closed position.

[0025]FIG. 4 is a plan view from below showing the device in the closedposition.

[0026]FIG. 5 is a plan view from above showing the device in the openposition.

[0027]FIG. 6 is a section on the plane VI-VI of FIG. 4.

[0028]FIG. 6A shows the same section as FIG. 6, but with the device inthe open position.

[0029]FIG. 7 is an enlarged detail of FIG. 6, showing the front end ofthe device during scraping.

[0030]FIG. 8 is a plan view from below, showing just the upper plate 6of FIG. 7.

[0031]FIG. 9 is a section on the plane IX-IX of FIG. 8.

[0032]FIG. 10 is a section on the plane X-X of FIG. 8.

[0033]FIG. 11 is a side view of a second embodiment of the invention.

[0034]FIG. 12 is a section on the longitudinal plane of symmetry of FIG.11.

[0035]FIG. 13 shows the same section as FIG. 12, but with the device inthe open position.

[0036] The device of the invention comprises an internally hollow,elongate handle M of variable cross-section and suitable shape,comprising a hollow body 1 defining a cavity 11, the upper face of whichis closed by an upper plate 6 slidable on the hollow body 1, to closeand alternately render accessible the cavity 11 thereof; a blade 20 ispositioned at the front end of the upper plate 6.

[0037] The hollow body 1 presents a rounded front portion 2 in which thecavity 11 is provided, and a flat intermediate portion 3 positionedadhering to the plate 6.

[0038] On the side walls of the hollow body 1 there are provided tworespective longitudinal ribs 4 projecting radially outwards from thesurrounding surface and extending in a longitudinal direction, toslidingly engage respective longitudinal seats 5 provided on the sidesof the upper plate 6 in order to form a connection which retains theplate 6 in contact against the hollow body 1 and enables it to sliderelatively in a longitudinal direction. The mutual connection means 4and 5 are such as to enable the upper plate 6 to slide on the hollowbody 1, in a longitudinal direction, between a forward end position(closed position) and a retracted position (open position). When theplate 6 is in its forward end position, its front portion 7 faces and isin contact with the front portion 2 of the hollow body 1, to close itscavity 11. In contrast, when in its retracted position, the cavity 11 istotally or partly uncovered.

[0039] The ribs 4 are present on that part of the body 1 to the rear ofthe front portion 2 and terminate where this portion 2 commences; atthat point they present two end stop teeth 8 which limit the travel ofthe plate 6. Likewise the longitudinal seats 5 are present on that partof the plate 6 to the rear of the front portion 7 and terminate wherethis portion 7 commences.

[0040] Consequently, when the plate 6 is in the closed position as inFIG. 6, the front portion 7 of the upper plate 6 projects beyond thestop teeth 8 and is released from the hollow body 1 (it is projectinglysupported elastically by the ribs 4 and only rests on the body 1); it isalso elastically deformable so that it can bend to rise in a transversedirection, when under load, from the front edge 2′ of the hollow body 1.

[0041] To the front end 7′ of the front portion 7 there is fixed a steelblade 20 having an active surface 21 perpendicular or nearlyperpendicular (i.e. forming an angle of about 80-100 degrees) to thelongitudinal axis of the front portion of the upper plate 6, and havingits cutting edge of arcuate profile, to act as a scraper the cutting orscraping edge of which is directed towards said hollow body and projectsdownwards therefrom.

[0042] Specifically, the blade 20 is formed from a truncated cone 25, ofwhich the axis is parallel to the longitudinal axis of the front portionof the hollow body 1, and the vertex faces forwards; its major base isflat or nearly flat, and defines said active surface 21; the edge of itsmajor base is circular and forms a cutting edge 22 the lower portion ofwhich is arranged to scrape along the donor bone. The height of thetruncated cone 25 is evidently much smaller than the diameter of themajor base, so that the angle (defining the cutting edge 22) formed, inthe axial section, between the active surface 21 and the conical surfaceis quite small and pointed.

[0043] The truncated cone 25 is joined to an axial rod 26, which extendsfrom the surface 21 and is fixedly inserted into the front end 7′ of theplate 7, with its axis parallel to the longitudinal axis of the frontportion of the handle M.

[0044] When the plate 6 is in the closed position, as in FIG. 6, theblade 20 projects axially forwards beyond the front end edge 2′ of thehollow body 1, and the lower part of the cutting edge 22 projectsslightly downwards beyond the same end edge 2′ of the body 1. When theplate 6 is in the open position, the cutting edge 22 of the blade is notaccessible from the outside.

[0045] The front end edge 2′ of the hollow body is positioned a shortdistance, in a radial direction, from the lower surface of the front end7′ of the upper plate 6 and also a short axial distance to the rear ofthe blade 20 to define, when the front portion 7 of the plate 6 is bentupwards, a narrow gap 16 for the passage of the bone flakes or shavingsD towards the interior of the cavity 11 in the hollow body (FIG. 7).

[0046] When in operation, the device of the invention is used in theclosed position for scraping. Typically, a force is applied to thedevice towards the bone B, and the front part 2 of the hollow body 1 ispositioned such that it adheres to and rests on the surface of the boneB. Alternatively, the front part 2 can form an angle with the surface ofthe bone B and rest on it only with its end edge 2′. As the cutting edge22 projects downwards from the end edge 2′ of the body 1, it comes intocontact with the donor bone and urges the front portion 7 upwards sothat it bends to separate from the body 1 and form said gap 16, which isabout 0.5 mm wide. At the same time, the cutting edge 22 is pressedagainst the bone with a substantially constant force, determined by thereaction to the elastic deformation of the portion 7. By moving thedevice parallel to the surface of the bone B, the blade 20 acts with itsactive surface 21 to produce shavings or flakes D which by virtue of theaction of the active surface 21 are collect in the cavity 11 via the gap16.

[0047] The constant thrust with which the cutting edge 22 is pressedavoids the danger of cutting or lacerating soft tissue close to thewithdrawal region, caused by excessive pressure, which could causeserious undesirable injury to blood vessels or, more dangerously, tonerves or tendons.

[0048] The deformation of the front portion 7 hence slightly distancesthe front edge 2′ of the hollow body 1 from the end 7′ of the plate 6,to increase the passage gap 16 for the bone shavings which enter thehollow body and are collected therein and preserved.

[0049] The front portion 2 of the hollow body 1 is shaped such thatalthough it maintains its length unaltered, it degrades in height toreach zero at the cutting edge 22 of the blade. Specifically, the lowerprofile (indicated by R in FIG. 7) of the lower surface 2 a of the frontportion 2 forms with the axis A of the blade 20, an acute angle Q in theaxial plane having a size of 5-30 degrees, i.e. such that whereas theprofile R substantially adheres to the surface of the bone B duringscraping, the active surface 21 of the blade 20 is inclined to thevertical at the surface of the bone B by a corresponding acute anglesuitable for scraping shavings and flakes D from the bone B. Thischaracteristic substantially improves the performance of the instrument.

[0050] Moreover, the front portion 2 of the hollow body 1 presents atits front end a rounded lower surface 2 a suitable for resting on thedonor bone.

[0051] By then pulling the upper plate 6 rearwards, the cavity 11 isuncovered to enable the accumulated bone particles to be extractedtherefrom.

[0052] At that end distant from the rounded end, the cavity 11 in thehollow body 1 terminates with a flat intermediate portion 3 lyingsubstantially in contact with the upper plate 6, and of sufficientlength such that, when the upper plate 6 is retracted completely, thecutting edge 22 of the blade lies on said flat part to remain protectedfrom accidental contact.

[0053] The embodiment shown in FIGS. 11, 12 and 13 differs from thepreceding illustrated embodiment in that the handle M comprises a frontportion M1 of longitudinal axis A1, which carries the blade 20, and arear portion M2 of longitudinal axis A2, to be gripped by the operator.

[0054] The longitudinal axes of the two portions M1 and M2 form acontained angle F, for. example of 15-25 degrees to determine anergonomic shape.

[0055] The angle F can be on one or other side with respect to the axisA2.

1. A device for withdrawing flakes or shavings from a donor bone byscraping, comprising an internally hollow handle (M) composed of ahollow body (1) with a cavity (11) and of slidable means for closing andrespectively rendering accessible the cavity (11), and scraper means(20) positioned at the front end of said slidable means and comprising agap for passage of the bone flakes or shavings into the cavity (11),characterised in that said slidable means comprise an upper plate (6)positioned on the upper side of the hollow body (1) to close the cavity(11) and slidable on this latter, its front portion (7) being not joinedto the hollow body (1) and being elastically deformable to move awayfrom the front edge of this latter when under load.
 2. A device asclaimed in claim 1, characterised in that said scraper means comprise ablade (20) positioned at the front end of said slidable plate (6), andhaving an active surface (21) perpendicular or nearly perpendicular tothe longitudinal axis of the front portion of the handle (M).
 3. Adevice as claimed in claim 2, characterised in that the profile of thecutting edge (22) of the blade (20) is arc shaped.
 4. A device asclaimed in claim 3, characterised in that the blade (20) is in the formof a truncated cone, with its axis (A) parallel to the longitudinal axisof the front portion of the hollow body (1) and its major base flat ornearly flat to define said active surface (21) of the blade (20) withits edge forming a cutting edge (22), the lower portion of which isarranged to scrape along the donor bone.
 5. A device as claimed in claim1, characterised in that the front end edge (2′) of the hollow body (1)is positioned a short distance from the lower surface of the front end(7′) of the upper blade (6) in a radial direction, and also a shortaxial distance to the rear of the blade (20), to define, when the frontportion (7) of the plate (6) is bent upwards, a narrow passage for thebone flakes or shavings (D) towards the interior of the cavity (11)
 6. Adevice as claimed in claim 1, characterised in that the front portion(2) of the hollow body (1) is shaped such that it degrades in height toits front end (2′) to reach zero at the cutting edge (22) of the blade,where it has a rounded lower surface (2 a) to rest on the donor bone. 7.A device as claimed in claim 5, characterised in that the lower profile(R) of the lower surface (2 a) of the front portion (2) forms with theaxis (A) of the blade (20), in the axial plane, an acute angle (Q) of5-30 degrees in size.
 8. A device as claimed in claim 1, characterisedin that the upper plate (6) is secured to the hollow body (1) by lateralconnection means (4, 5) such that it can slide relative thereto, in alongitudinal direction, between a forward end position, in which itcloses the cavity (11) of the hollow body (1) and the blade (20)projects forwards beyond the front end edge (2′) of the hollow body (1),and a retracted position in which the cavity (11) is at least partiallyuncovered and the cutting edge (22) of the blade (20) is inaccessiblefrom the outside.
 9. A device as claimed in claim 1, characterised inthat the connection means (4, 5) between the hollow body (1) and theupper plate (6) terminate at a certain distance from the front edge (2′)of the hollow body (1) such that the front portion (7) of the platewhere the blade (20) is positioned is projectingly supportedelastically.
 10. A device as claimed in claim 1, characterised in thatsaid handle (M) comprises a front portion (M1) which carries the blade(20), and a rear portion (M2) to be gripped by the operator, saidportions (M1 and M2) having longitudinal axes (A1, A2) which form acontained angle F to define an ergonomic shape.